This invention relates to a fuel-metering system for externally ignited internal combustion engines with compression of the air-fuel mixture, which system comprises a suction tube for the intake of air in which an air-measuring device and a randomly adjustable throttle valve are arranged in sequence, and in which an essentially proportionate amount of fuel is metered into the amount of air flowing therethrough, the proportionality of the fuel amount being adjustable by means of controlling a bypass circumventing the air-measuring device in dependence on engine data.
Fuel-metering systems are already known in which this proportionality between fuel amount and air amount is adjustable in dependence on engine data, in which however, an optimal ratio in the mixture cannot be attained, even though the same rate of air flow prevails at several operating levels in the engine performance graph, as the requirements with regard to the air-fuel mixture are different ones for these levels.